Metal (SS) Engine cradle to set prop angle...

I'm am about to glass in the the engine bed stringers for a Yanmar 3GM30.
I am indecisive whether to make up the stringer in wood & glass with the engine angle ramp as part of the stringer, all glassed with epoxy & Db, or
just glass in the stringers and weld up a SS angle cradle to sit atop? Will the metal cradle cause more vibration?
The one piece timber engine bed would have holesaw cutouts for washers & nuts.
(45mm timber)

 

A single piece engine cradle is a good idea. You can incorporate a catch pan under it, to contain the oil that eventually manages to find it's way out of the engine or spills. Yep, some angle, through bolted or lagged to the stringers is a typical arrangement. Of course, you'll still want mounts integrated into your cradle to isolate vibration.

 

Thanks Par. I guess you mean by A single piece engine cradle is a good idea. that is all wood & glass?
If we run 150mm stringers then we need another 200mm of metal engine stand to get to the required level.
This could prove to be non-damping as opposed all wood and glass?

 

I was under the impression you intend a metal cradle and will rebuild the engine beds.

I'm not sure why you want a cradle, but I can see situations where using one would have advantages.

The engine beds can be incorporated into (good idea) the stringer or bolted to it. This assumes the stringers are stiff enough to accept the loads of the beds.

Engines sit on mounts. The mount can be of several styles, but all incorporate a rubber section to isolate the engine from the boat. Most mounts are adjustable, meaning they can be raised or lowered, permitting shaft alignment. Other types of mounts require shims which raise or lower the mount. These are more difficult to align, but were used for many generations before screw style of mounts became popular.

Rather then try to build something that does this, I'd recommend you purchase real mounts. Carefully measure and arrange your engine bay to receive the mounts and engine as an assembly, then mark the mount fastening bolt locations on the engine beds. Remove the assembly and the mounts, drill for the fasteners and bolt down the mounts. Then install the engine on the mounts and align it to the shaft by conventional means at the coupler flange.